LAB MODULE 5: GLOBAL TEMPERATURE PATTERNS

Note: Please refer to the GETTING STARTED lab module to learn how to maneuver

through and answer the lab questions using the Google Earth ( ) component.

KEY TERMS

You should know and understand the following terms:

Air temperature Heat index Temperature anomalies

Altitude Kelvin (K) Temperature averages

Ambient temperature Latitude Thermopause

Axial Tilt Maritime effect Thermosphere

Celsius (C) Mesopause Tropopause

Continentality, or

Continental effect

Mesosphere Troposphere

Stratopause Urban heat island

Environmental Lapse Rate Stratosphere Urban heat island effect

Exosphere Structure of the atmosphere Wind chill

Fahrenheit (F) Surface temperature

LAB MODULE LEARNING OBJECTIVES

After successfully completing this module, you should be able to the following

tasks:

 Describe the differences between air and surface temperature

 Explain heat index and wind chill

 Explain the urban heat island effect

 Describe the structure of the atmosphere

 Describe large scale factors influencing temperature

 Describe local factors influencing temperature

2

INTRODUCTION

This lab module explores the global surface and air temperatures of Earth and

Earth’s atmosphere. Topics include the structure of the atmosphere, local and

global factors influencing temperature, and temperature anomalies. The modules

start with four opening topics, or vignettes, which are found in the accompanying

Google Earth file. These vignettes introduce basic concepts of the internal structure

of the Earth. Some of the vignettes have animations, videos, or short articles that

will provide another perspective or visual explanation for the topic at hand. After

reading the vignette and associated links, answer the following questions. Please

note that some links might take a while to download based on your Internet speed.

Expand the INTRODUCTION folder.

Read Topic 1: Surface and Air Temperature

Question 1: How do the surface temperatures of the countries in the

northern latitudes (for example, Canada, Iceland, Norway, and Russia)

compare to those of northern Africa (for example, Algeria, Egypt, Libya,

Morocco, and Sudan)?

A. The temperatures are higher in the northern latitudes during summer

months when net radiation is higher.

B. The temperatures are lower in north Africa during the summer months

when net radiation is higher in northern latitudes.

C. Temperatures are lower in northern latitudes year-round.

D. Temperatures are only lower in the northern latitudes during winter

months.

Read Topic 2: Measuring Temperature

Question 2: Considering water freezes (or alternatively, melts) at 0˚C,

determine from the map which countries or landmasses have an annual

mean temperature around 0˚C.

A. Canada and Norway

B. The United States and the United Kingdom

C. Greenland and Antarctica

D. Russia and Antarctica

3

Read Topic 3: Heat Index and Wind Chill

Question 3: The heat index on a warm day (86˚F or 30˚C) when the

relative humidity is 50% is:

A. 87F B. 90F

C. 31C D. 33F

Read Topic 4: Human Interaction

Question 4: Identify three negative impacts of heat islands.

A. Increased energy consumption, elevated greenhouse gases, improved

water quality

B. Compromised human health, lower energy consumption, lower water

quality

C. Decreased greenhouse gases, higher energy consumption, compromised

human health

D. Increased greenhouse gases, greater air pollution, increased energy

consumption

Collapse and uncheck the INTRODUCTION folder.

4

GLOBAL PERSPECTIVE

Perhaps you recall news reports on extreme temperature-related weather patterns,

such as the 2010-2011 colder-than-normal winter in the western USA, or the 2003

European summer heat wave (which led to more than 35,000 deaths). These

examples are temperature anomalies, as they deviate significantly from

temperature averages that are based on decadal (or longer) year records.

Temporary temperature anomalies are usually due to non-permanent weather

phenomena like a passing storm or seasonal drought; however, more permanent

temperature anomalies could signify the presence of urban heat islands, and if

widespread, global climate change. Temperature anomalies can have significant

impacts on farming and ranching, recreation, and even human health.

Expand the GLOBAL PERSPECTIVE folder and then check Temperature

Anomalies in January. To close the citation, click the X in the top right corner

of the window.

This imagery uses the following color scheme to show land surface temperature

anomalies during the month of January 2011 as compared to average conditions for

the month in 2000 to 2008:

 Red – warmer-than-average temperatures

 Blue – cooler-than-average temperatures

 Black – no data

Temperatures ranged from 12˚C below to 12˚C above the normal January

temperature.

Verify that Borders and Labels and Places are checked in the Layers panel. To note, you might have to zoom in or out for the location name to appear.

Double-click and select Location A.

Question 5: What is the name of this US county? (You might have to zoom

in to see place names.)

A. Lasalle

B. Bureau

C. Putnam

D. Marshall

Question 6: Is the temperature anomaly warmer or colder?

A. The anomaly is warmer

5

B. The anomaly is colder

C. There is no anomaly, temperature is the same

D. Unable to discern

Double-click and select Location B.

Question 7: What is the name of the European city?

A. Ludres

B. Frouard

C. Nancy

D. Toul

Question 8: Is the temperature anomaly warmer or colder?

A. The anomaly is warmer

B. The anomaly is colder

C. There is no anomaly, temperature is the same

D. Unable to discern

Double-click and select Location C.

Question 9: What is the name of the capital city?

A. Windhoek

B. Okahandja

C. Pretoria

D. Khomas

Question 10: Is the temperature anomaly warmer or colder?

A. The anomaly is warmer

B. The anomaly is colder

C. There is no anomaly, temperature is the same

D. Unable to discern

Uncheck Temperature Anomalies in January.

Double-click and select Temperature Anomalies in August. To close the

citation, click the X in the top right corner of the window.

This imagery shows land surface temperature anomalies during the month of

August 2003.

6

Return to Location B.

Question 11: What is the temperature anomaly (in °C)?

A. -12°C

B. -4°C

C. 4°C

D. 10°C

Question 12: How does this anomaly compare to the one in January 2011?

A. The anomaly is warmer

B. The anomaly is colder

C. There is no anomaly, temperature is the same

D. Unable to discern

Collapse and uncheck the GLOBAL PERSPECTIVE folder.

STRUCTURE OF THE ATMOSPHERE

The structure of the atmosphere impacts temperature. To begin, Earth’s

atmosphere is not uniform, but is comprised of layers. The layer closest to the

surface is called the troposphere. Because the troposphere’s temperature is based

on long wave radiation emitted from the Earth’s surface, temperature decreases

with elevation in this layer of the atmosphere. This change in temperature with

altitude is called the environmental lapse rate.

Click STRUCTURE OF THE ATMOSPHERE. Watch the animation and answer

the following questions:

Question 13: Why does the temperature increase in the upper portion of

the stratosphere?

A. Because long wave radiation is heating the earth’s surface

B. Because ozone blocks ultra-violet radiation and releases heat

C. Because clouds are able to trap heat

D. Because heat is trapped in this portion of the atmosphere

Question 14: Because temperature increases as altitude increases in the

stratosphere, is the environmental lapse rate positive or negative?

A. The lapse rate is positive

7

B. The lapse rate is negative

C. The lapse rate is zero

D. Unable to discern

Question 15: Why are temperatures in the thermosphere so high?

A. Because this layer is closest to the sun

B. Because of intense solar radiation

C. Because there are so few molecules

D. Because of the lack of pollutants

Question 16: Would it feel hotter on a warm summer day in the

thermosphere or the troposphere? (Hint: Think composition!)

A. In the thermosphere because temperature reaches over 1000F

B. In the troposphere because temperature reaches over 1000F

C. In the thermosphere because of the intense solar radiation

D. In the troposphere because there are more air molecules to retain heat

The environmental lapse rate can be used to determine a given temperature of a

location, provided that the lapse rate and altitude are known. The standard

environmental lapse rate as you go up in altitude is 6.4 ˚C/1000m. In other words,

as you go up 1000 meters, the temperature decreases 6.4˚C

For the following questions, however, assume a negative environmental lapse rate

of 6.4˚C/1000m.

So how do you solve this? Here is an example:

You have a location – Town M. Town M that has an altitude of 100m and its air

temperature is 10˚C. At 1000m the air temperature is different – but what is it?

How do we figure out the temperature at 1000m?

To solve:

First, make sure you know the initial temperature and distance between the start

location and the end location.

Initial temperature: 10˚C

Distance: 1000m – 100m = 900m

Next, let’s set up the equation:

Environmental lapse rate = x/distance

8

Where x is the unknown air temperature for Town M. Plug in the numbers and

units:

6.4˚C/1000m = x/900m

Now we multiply 900m on both sides.

6.4˚C*900m/1000m = x/900m * 900m

6.4˚C*900m/1000m = x

The m/m means that the meters cancel out, leaving only ˚C as a unit. If we do the

math, our answer is as follows:

x = 6.4˚C*900m/1000m

x = 5.76˚C

This value means your change in temperature was 5.76˚C. Now, take the initial

temperature value (10 ˚C) and subtract the calculated x temp (5.76˚C) from it.

10 ˚C – 5.76˚C = 4.24 ˚C

Note that this is a negative environmental lapse rate – meaning you subtract going

up in elevation, and add going down in elevation.

Question 17: The altitude in town N is 1000m and the air temperature is

22˚C. What is the air temperature (in˚C) at 3000m?

A. 22˚C – (3000m-1000m)*6.4/1000m = 9.2˚C

B. 22˚C + (3000m-1000m)*6.4/1000m = 34.8˚C

C. 22˚C – (3000m-1000m)*5.76/1000m = 10.5˚C

D. 22˚C – (3000m-1000m)*5.76/1000m = 33.5˚C

Question 18: The altitude in town P is 1000m and the air temperature is

18˚C. What would be the temperature (in ˚C) of Town P if it were located

instead at 500m?

A. 18 – (1000m-500m) *6.4/1000m = 21.2˚C

B. 18 – (1000m-500m) *6.4/1000m = 14.8˚C

C. 18 + (1000m+500m) *6.4/1000m = 27.6˚C

D. 18 – (1000m+500m) *6.4/1000m = 9.0˚C

Uncheck the STRUCTURE OF THE ATMOSPHERE folder.

9

FACTORS INFLUENCE AIR TEMPERATURE

Global Scale Factors

There are several global-scale factors that influence air temperature. These include

latitude, axial tilt (and length of day), and time of day.

Latitude

Latitude affects net radiation (energy). Locations in lower latitudes (for example,

near the Equator) have net gain (or surplus) of radiation, while higher latitudes (for

example, near the North or South Pole) have a net loss (or deficit) of radiation.

Where there is a surplus of energy, there are higher air temperatures. Thus,

tropical and sub-tropical regions have a higher annual average air temperature than

polar and sub-polar regions.

Axial Tilt

The tilt of the Earth’s axis is one of the major reasons the Earth has seasons. The

location where the most energy from the Sun (as sunlight) directly hits the Earth’s

surface is called the subsolar point. In the Northern Hemisphere in June, the

subsolar point is at or near the Tropic of Cancer (23.5 degrees North of the

Equator) and the days are longer. In contrast, the subsolar point is furthest from

the Northern Hemisphere in December (23.5 degrees South of the Equator) and the

days are shorter. As a result, the air temperature in the Northern Hemisphere is

higher in June (thereby summer) and lowers in December (thereby winter).

Time of day

Lastly, the time of day affects air temperature. Usually, the temperature is warmer

during the day and cooler at night. Local noon time is the peak of solar radiation.

However, there is a temperature lag, and the peak air temperature is usually a few

hours after the peak of solar radiation. This is because the sunlight reaching the

Earth’s surface needs time to heat it up, and then re-radiate the energy back into

the atmosphere as long wave (thermal) radiation.

Expand the AIR TEMPERATURE folder and then expand the Global-Scale

Factors folder.

Select Day Temperatures in December. To close the citation, click the X in

the top right corner of the window.

Double-click and select Location D.

10

Question 19: Estimate the average monthly daytime temperature in

December for this location.

A. 0°C

B. 5°C

C. 15°C

D. 25°C

Question 20: Record the latitude for this location.

A. 58N

B. 58S

C. 34N

D. 34S

Double-click and select Location E.

Question 21: Estimate the average monthly daytime temperature in

December for this location.

A. 0°C

B. 5°C

C. 10°C

D. 25°C

Question 22: Record the latitude for this location.

A. 33S

B. 33N

C. 84N

D. 84S

Question 23: What global-scale factor(s) accounts for the temperature

difference between Locations D and E? Check all that apply.

A. Latitude

B. Axial tilt

C. Time of day

D. All of the above

Click Night Temperatures in December. To close the citation, click the X in

the top right corner of the window.

Double-click and select Location F.

11

Question 24: Estimate the average monthly night time December

temperature for location F.

A. -20°C

B. 0°C

C. 5°C

D. 15°C

Double-click and select Location G.

Question 25: Estimate the average monthly night time December

temperature for location G.

A. -15°C

B. 0°C

C. 5°C

D. 10°C

Question 26: Account for the temperature difference you recorded for

Location F and G.

A. Latitude

B. Axial tilt

C. Time of day

D. All of the above

Question 27: What global-scale factor(s) accounts for the temperature

difference you recorded between Locations E and F?

A. Latitude

B. Axial tilt

C. Time of day

D. All of the above

Collapse and uncheck the Global-Scale Factors folder.

Local Scale Factors

In addition to large-scale factors influencing temperature, there are also three

notable local-scale factors; namely, proximity to a large body of water (maritime

effect versus continentality), altitude, and the urban heat island effect.

12

Maritime versus Continental

The maritime/continental

factor refers to the

proximity to a large body of

water. If a location is

located near the ocean (like

Seattle, Washington, USA),

its temperature is

influenced by a maritime

effect. This means that

average temperatures are

moderated, and are not

significantly higher than the

average in the summer or

significantly lower than the

average in the winter months. Conversely, locations experiencing a continental

effect on their temperatures (like Lincoln, Nebraska, USA) have colder

temperatures in the winter and warmer temperatures in the summer months.

Figure X illustrates the maritime/continental effect on temperature. In the winter

months, Seattle, Washington is up to 16F warmer than Lincoln, but in the summer

months, Lincoln is 14F warmer than Seattle.

Altitude

Altitude is the second local

factor affecting

temperature. In general,

locations at a lower altitude

have a warmer temperature

than those at a higher

altitude. The temperatures

of both Denver, Colorado

and Kansas City, Missouri

are located roughly at

latitude of 39°N, and are

influenced by the

continental effect. However,

Denver is located at approximately 5,280 feet, while Kansas City is located at

approximately 973 feet in elevation. Figure 2 shows that on average, temperatures

are warmer in Kansas City, MO than in Denver, CO, owing in large part to a

difference in altitude.

Figure 2. Average monthly temperatures for Denver and Kansas City.

Figure 1. Average monthly temperatures for Seattle and Lincoln.

13

Urban Heat Island

An urban heat island is a

phenomenon in which

urban areas are generally

warmer than the

surrounding rural areas.

This is due to the amount

of impervious surfaces

such as roads, buildings

and parking lots found in

urban centers. These

surfaces, plentiful within

most urban areas, tend to

emit more long wave radiation (heat energy) than do rural areas dominated by

natural vegetation, crops or soil.

Figure 3 illustrates the urban heat island effect. Atlanta is a major city in the US,

while Acworth is a small city located northwest of downtown Atlanta. The graph

shows that temperatures are slightly warmer in urban Atlanta, compared to

suburban Acworth.

Before you begin this section, make sure that you have Borders and Labels

selected under the Layers panel in Google Earth.

Expand the Local Scale Factors folder.

Check Average Temperature in July.

Double-click and select Location H.

Question 28: Estimate the average monthly July temperature for Location

H.

A. 0°C

B. 5°C

C. 15°C

D. 25°C

Double-click and select Location I.

Question 29: Estimate the average monthly July temperature for Location I.

A. 0°C

Figure 3. Average monthly temperatures for Atlanta and Acworth.

14

B. 5°C

C. 15°C

D. 25°C

Question 30: What of these local-scale factors – continental versus

maritime effect, altitude, or urban heat island effect – is most influencing the

difference in temperature between Locations H and I?

A. Maritime effect

B. Altitude

C. Urban heat island

D. None of the above

Double-click and select Location J.

Question 31: Estimate the average monthly July temperature for Location J.

A. 0°C

B. 5°C

C. 15°C

D. 30°C

Double-click and select Location K.

Question 32: Estimate the average monthly July temperature for Location

K.

A. 0°C

B. 5°C

C. 15°C

D. 25°C

Question 33: What of these local-scale factors – continental versus

maritime effect, altitude, or urban heat island effect – is most influencing the

difference in temperature between Locations J and K?

A. Maritime effect

B. Altitude

C. Urban heat island

D. None of the above

15

Double-click and select Location L.

Question 34: Estimate the average monthly July temperature for Location L.

A. 0°C

B. 5°C

C. 15°C

D. 20°C

Double-click and select Location M.

Question 35: Estimate the average monthly July temperature for Location

M.

A. 0°C

B. 5°C

C. 15°C

D. 20°C

Question 36: What of these local-scale factors – continental versus

maritime effect, altitude, or urban heat island effect – is most influencing the

difference in temperature between Locations L and M?

A. Maritime effect

B. Altitude

C. Urban heat island

D. None of the above

Question 37: What of these local-scale factors – continental versus

maritime effect, altitude, or urban heat island effect – would most likely show

same trend in average monthly temperature in January as in July? (Hint:

Figures 1-3)

A. Maritime effect

B. Altitude

C. Urban heat island

D. None of the above

16

Question 38: What of these local-scale factors – continental versus

maritime effect, altitude, or urban heat island effect – would likely show an

opposite trend in average monthly temperature in January as in July? (Hint:

Figures 1-3)

A. Maritime effect

B. Altitude

C. Urban heat island

D. None of the above

Collapse and uncheck the Local-Scale Factors folder. You have completed Lab

Module 5.